Semiconductor devices are currently in widespread use in a variety of electronic components. Semiconductor devices may retain information, as in a non-volatile memory device, or perform a calculation, such as in a microprocessor or in a digital signal processor. Semiconductor devices consume a certain amount of power to perform their tasks. However, as semiconductor devices consume power, they also dissipate heat. Often times the amount of power consumed generates a considerable amount of heat. If the heat generated by the semiconductor device exceeds a certain range, the semiconductor device may fail. In order to prevent the semiconductor device from failing as a result of generating too much heat, a temperature sensing circuit and a temperature sensor are often deployed to monitor the temperature of the semiconductor device. The temperature sensor monitors the heat generated by the semiconductor device and generates an analog signal as a result. The analog signal is typically a voltage or a current.
Often times, the temperature sensing circuit and the temperature sensor are connected with an analog-to-digital converter which converts the analog signal to a digital value. The digital signal can be input or read by the semiconductor device or by another device. The analog-to-digital converter performs this conversion using a technique called sampling. That is, as the analog signal passes through the analog-to-digital converter, samples are taken at a given interval. For example, if the sampling rate of the analog-to-digital converter is 10 Hz, then ten samples of the analog signal will be taken each second. The accuracy of the sample taken depends upon the accuracy of the analog-to-digital converter. For example, an analog-to-digital converter which has a defined word length of ten bits, can store ten bits of information for every sample. Additionally, an analog-to-digital converter which has a defined word length of eight bits, can store eight bits of information for every sample, which is less than ten bits of information. While larger word lengths are more accurate, they require more power than smaller word lengths.
In certain electronic devices which use an analog-to-digital converter and have limited power, such as laptop computers and personal digital assistance, there is a need for a device or method which could reduce the amount of power consumed by the analog-to-digital converter. Additionally, in certain situations, such as when the heat generated by the electronic device exceeds a certain range, there is also a need for a device or method which could reduce the amount of power being consumed by the electronic device, in order to prevent failure of the electronic device.
The present invention is defined by the following claims, and nothing in this section should be taken as a limitation on those claims. By way of introduction, the preferred embodiments described below relate to a tunable analog-to-digital converter which generates samples having M-bits for use with an operating circuit. The operating circuit generates a first enable signal to instruct the analog-to-digital converter to turn on. Additionally, a sensor generates an analog signal in response to a condition. The tunable analog-to-digital converter includes a primary analog-to-digital converter which receives the analog signal and converts the analog signal to a primary digital signal upon receipt of the first enable signal. The tunable analog-to-digital converter also includes a comparator and a secondary analog-to-digital converter. The comparator compares the value of the primary digital signal to a predetermined value and generates a second enable signal depending on the value of the primary digital signal and the predetermined value. The secondary analog-to-digital converter receives the analog signal and converts the analog signal to a secondary digital signal upon receipt of the second enable signal. The secondary digital signal comprises less than M-bits.
The preferred embodiments further relate to a method for operating a tunable analog-to-digital converter which generates samples having M-bits for use in an operating circuit. The operating circuit generates a first enable signal to instruct the analog-to-digital converter to turn on. Additionally, a sensor generates an analog signal in response to a condition. The method includes converting the analog signal to a primary digital signal upon receipt of the first enable signal. The method further includes generating a second enable signal depending on the value of the primary digital signal and a predetermined value, and converting the analog signal to a secondary digital signal upon receipt of the second enable signal. The secondary digital signal comprises less than M-bits. Further aspects and advantages of the invention are discussed below in conjunction with the preferred embodiments.